Hardness tester



Dec. 22, 1953 H. BROSCHKE HARDNESS TESTER Filed Oct. 20, 1951 W14 IIIIIIII Patented Dec. 22, 1953 UNITED STATES PATENT OFFICE HARDNESS TESTER Application October 20, 1951, Serial No. 252,224 6 Claims. (CI. 73-81) My present invention relates to improvements in apparatus for testing the hardness of various materials.

Hardness testers, especially small test apparatus, have heretofore been known in which a holder for a diamond point is fastened on a holding arm. In such apparatus it has been found that the arm and the column supporting it undergo a slight bending when the apparatus is in use and the loading weight is set on the diamond holder. When the diamond is then pressed into the specimen, the bending goes back whereby a slight sidewise shifting of the diamond point is caused. The edges of the impressions are in this case inexact.

This defect is obviated by my invention which provides that the diamond holder is secured to the holding arm through means yieldable in a direction normal to the direction of pressure as, for example, leaf springs or bar springs. The springs can be mounted in such a way that during the pressing process they will serve under compression or under tension. They transmit the pressure required to impress the diamond point, which is, for example, attained by a deposit-ed weight. If, then, the holder arm and the carrying column are deflected a slight amount by this weight and this deflection is released by the setting down of the diamond point on the specimen, a sidewise shifting of the diamond point is avoided through sidewise bending of the springs.

The invention is illustrated by way of example in the accompanying drawings, in which Fig. l is a side view of apparatus embodying the invention;

Fig. 2 is a longitudinal section of the diamond holder and springs in tension;

Fig. 3 is a section taken on line III--III of Fig. 2;

Fig. 4 is a vertical section of a modification embodying two systems of leaf springs, and

Fig. 5 isa section taken on line V-V of Fig. 4.

In the embodiment illustrated in Fig. 1 a holder arm 2 is mounted on a column I by means of a guide 3. In the holder arm 21s carried a body 6, having a supporting surface 4 for a weight 5. As shown in Figs. 2 and 3, in the body 6 leaf springs 1 are fastened at their lower ends 8. At their upper ends 9 the leaf springs carry the diamond holder I which contains the diamond H.

In use a specimen I is placed on a specimen support [6 below the diamond point or indenter ll so that when the weight 5 is placed on the platform 4 and the indenter rests on the specimen 2 l5 the indenter may sink into the specimen l5 under weight 5 without side stresses that might shift the point of the indenter sidewise.

Figs. 4 and 5 disclose an embodiment with opposing leaf springs. At the lower end of the body 6 two leaf springs l2 are secured, whose upper ends carry an intermediate piece I 3. At the lower end of the intermediate piece leaf springs It are secured whose planes are at right angles to the planes of the leaf springs I2. The diamond holder is secured to the upper ends of the leaf springs M.

In both embodiments illustrated, the springs are placed in tension during the step of impressing. The invention is not limited to this, for one can without difficulty so arrange the springs that they are under compressive stress.

Having described my invention, what I claim is:

1. A hardness tester which comprises a specimen support, a weightable indenter above said specimen support to move downwardly upon weighting toward said support, a holder carrying said indenter, and supporting elements each attached to said holder at a point spaced vertically from its attachment to said indenter and displaceable sidewise between its attachment to said indenter and to said holder respectively.

2. The hardness tester of claim 1 in which said supporting elements are leaf springs.

3. The hardness tester of claim 2 in which said leaf springs are spaced equiangularly about the indenter.

4. The hardness tester of claim 1 in which said holder comprises a column and an arm extending sidewise therefrom on which said supporting elements and indenter are carried.

5. The hardness tester of claim 4 in which said arm is provided with a recess spaced from said column and with a body fixed vertically in said recess to which said supporting elements are attached.

6. The hardness tester of claim 5 in which said body is recessed and in which said indenter projects into said recess of said body.

HEINRICH BROSCHKE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,422,634 Riepert et a1. June 17, 1947 FOREIGN PATENTS Number Country Date 603,531 Germany Oct. 3, 1934: 

